1. Field of the Invention
The present invention relates to a method for operating a liquid crystal display, and more particularly, to a method for operating a liquid crystal display (LCD) to prevent the appearance of blur.
2. Background of the Related Art
In general, an LCD has a system of cells in which a thin film transistor (TFT) is positioned in each cell of the LCD. A large-sized LCD having a large number of cells has been the subject of research because it has a high contrast ratio with a wide and linear gray scale capability for a moving image. Moreover, a large-sized LCD has application to large displays, such as High Definition Television (HDTV) because a large-sized LCD can be fabricated such that all of the cells are operational resulting in a high picture quality.
A related art LCD will be explained, with reference to the attached drawings. FIG. 1 illustrates a block diagram of a related art LCD. The related art LCD shown in FIG. 1 is provided with a Low Voltage Differential Signaling (LVDS) module 1 for receiving a picture data for an LCD panel 2 and providing data enable signals, vertical synchronizing signals, horizontal synchronizing signals and a system clock to a timing controller 3. In addition, the LVDS 1 provides picture data to a memory part 5 of the system. Data signals are provided to a data driving part 8 of the LCD panel 2 and gate signals are provided to a gate driving part 9 of the LCD panel 2 by the timing controller 3 in response to the data enable signals, vertical synchronizing signals, horizontal synchronizing signals and the system clock. The data driving part 8 provides data to the cells 7 of the LCD panel 2 while the gate driving part 9 drives gates of TFTs in the cells 7 of the LCD panel 2 such that cells 7 receive data. The memory part 5 receives the data signals from the timing controller part 3 and also receives picture data from the LVDS 1. The picture data is R, G, and B data. Using the picture data and the data signals, the memory part 5 provides even and odd numbered signals required for driving data in the data driving part 8 of the LCD panel 2.
The LCD panel 2 is provided with a plurality of gate lines 10 and a plurality of data lines 11 formed in a matrix shape that define the cells 7 of the LCD panel 2. Each cell has a TFT (not shown) connected to a pixel electrode. A back light 15 that can be a light conduit type is formed on the backside of the LCD panel 2 for illuminating all of the cells on the back side of the LCD panel 2. The data level or voltage value of the data supplied to the pixel electrode through the TFT determines the amount of light transmittance that will occur through the cell from the back light 15.
FIG. 2 depicts a timing diagram for the related art LCD illustrated in FIG. 1. The timing for the related art LCD shown in FIG. 1 will be explained briefly. Although, in general, the timing of a gate signal, such as a scanning signal, varies with a resolution of the LCD, the timing diagrams for operating the related art LCD will be explained based on five scanning signals to simplify explanation. FIG. 2 illustrates a timing diagram for the related art LCD illustrated in FIG. 1. Referring to FIG. 2, the gate driving part 9 provides gate signals G1, G2, G3, G4 and G5 to the gate lines 10 for turning on the TFTs while the data driving part 8 provides data signals D to data lines 11. More specifically, the gate signals turn on and then turn off each TFT in sequence such that the data signals D are transmitted through the TFTs to the cells of the LCD panel only when the TFTs are turned on. On a screen for displaying an image, all of the gate lines are sequentially scanned such that all of the TFTs for the cells of the LCD panel are turned on and then turned off during one frame.
The related art LCD has a problem in that images of a first frame overlap into a second frame due to the response time of a cell when data for a cell is changed to new data in the next frame since light can still momentarily transmit through the cell. FIG. 3 illustrates the response of a cell changing from one data state to another data state. As shown in FIG. 3, the cell has a first frame If that has a first data level D1. Subsequently, the data in the cell is changed to a second data level D2 during a second frame 2f. However, there is a delay in the cell transferring from the first data level D1 to the second data level D2 that causes the appearance of blur on the screen. It is appearance of this blur caused by the delay in a cell transferring from one data level to another data level that impedes the use of an LCD panel as a HDTV.